Of all the possible sensory disabilities, visual impairment is generally considered to be the one that has the greatest impact on a person's everyday life. A person's vision system provides them with information that forms a major basis for his mobility and ability to perform navigational tasks. A visually impaired person, such as one who is blind, incurs many challenges and inconveniences in his everyday life, especially with regard to his mobility and his ability to perform navigational tasks. For example, a visually impaired person can experience great difficulty accomplishing tasks such as moving about a room, finding a passageway out of the room or into a new room, navigating to a desired destination, and finding a desired object in his physical environment. A visually impaired person often relies upon his intact senses, which may be hearing and/or touch, to accomplish these tasks. In other words, a visually impaired person often relies upon information from his auditory system and/or his tactile system to compensate for his lack of sight information. This is commonly referred to as “vision substitution.”